Microsoft Security Essentials Antivirus software is a good place to start, and Microsoft Security Essentials is an excellent option. It's been rated very highly in head-to-head tests and is every bit as good (if not better) than programs like Norton Antivirus, AVG, and Avast. Best of all, Security Essentials is free "for use in your home-based small business," as specified in the license agreement. 
OpenOffice or Lotus Symphony OpenOffice is widely regarded as the top free alternative to Microsoft Office, and it includes the same range of applications. There's Writer for word processing (Word), Calc for spreadsheets (Excel), Impress for presentations (PowerPoint), Base for databases (Access), and Draw for creating images and diagrams for your documents and slideshows. 
Symphony is actually based on OpenOffice, and though its interface is quite different, it's well worth a look. If you're a fan of using tabs in your Web browser, you might really like the fact that Symphony handles documents the same way. Symphony is also a bit slimmer than OpenOffice, offering the three main programs you'll likely need: word processor, spreadsheet, and presentations.
OpenClipArt Finding free images to use in things like flyers and postcards that you might want to print for your business can be a lot of work. Fortunately, OpenClipArt has a massive collection with hundreds of megabytes of public domain images. There's plenty of awesome stuff, too, like the contributions from rg1024.
GnuCash Free accounting software? You bet. I've seen how much money a lot of people shell out for big-name accounting programs, so you owe it to yourself to take a look at GnuCash. It's got all of the important features that an accounting app should have: general ledger, vendors, bills, taxes, check printing -- it's all there. GnuCash is also compatible with Quicken's .QIF files and the Open Financial Exchange (.OXF) data that many banks provide. 
GanttProject A good project management tool may also be something you require for your business. They can be a great way to make sure that you meet deadlines and allocate resources in a timely and logical manner. GanttProject is (no surprise) a lot like Microsoft Project -- it can even import and export MS-compatible files! 
Windows Live Mail or Thunderbird + Lightning Microsoft's free email program has come a long way since the days of Outlook Express. Windows Live Mail is surprisingly good, and it offers a lot of the same features you'll find in its business-oriented cousin, Microsoft Outlook. Apart from handling your email, Live Mail also includes a calendar, manages contacts, and incorporates an RSS news reader for subscribing to updates from your favorite Web sites. Another option is Mozilla Thunderbird and the Lightning add-on, which adds a calendar component and a tasks list. One other thing that this pairing lets you do, which Live Mail doesn't, is to create alarms / reminders. Used together, Thunderbird and Lightning definitely provide more business-class features than WLM. 
Evernote Do you need a full-featured note-taking tool? Do you want one that you can use on your iPhone, iPad, or Android smartphone as well as your laptop or desktop computer? Evernote is about as good as they come, and it's packed with awesome features -- from voice memos to photo notes to clippings from Web pages you visit. Better still, Evernote makes organizing your collection a breeze, and finding a specific note is super easy thanks to its tagging features and flexible search. 
dsBudget If you leave all the GnuCash-esque work to your accountant and just need a simple way to create and manage your budget, dsBudget is worth checking out. The screenshot above shows a non-business setup, but the program is totally customizable. You create your own income, deductions, and categories. dsBudget also produces nice-looking charts to help you visualize your finances. 
Picture Timeclock If you have a few employees -- say, a small cleaning, landscaping, or painting crew -- a decent timeclock is a great way to keep tabs on their hours. About 5 years ago, the mechanical punch clock at my day job broke, and we had to find a replacement. Those things aren't cheap, so we looked for an alternative. With a beaten-up old computer that you could score for $50 at a second hand shop, we put together a replacement using Picture Timeclock. It's an awesome, free application with loads of features like detailed reporting, multiple departments, and the ability to take a picture via a webcam whenever someone punches in or out. It handles our 12-man retail shop with ease. edit: you can also download picture timeclock here.
Calibre Most of the documentation that you need for your business -- tax forms, manuals, etc. -- is in an electronic format at this point. Why not have a special program on your system to catalog and organize those documents? Calibre is like an eBook library, and it's the perfect tool for maintaining your important business docs. It can handle just about any common format, including ePub purchases from places like Amazon. Calibre is also a great way for less-technical types to stay on top of online news via RSS feeds. It's got built-in support for over 300 sources including the New York Times and The Wall Street Journal.
PDFCreator Adobe Acrobat's PDF files are a great way to share documents. Not all programs allow you to save files as PDFs, however, which is where PDFCreator comes in. The program installs itself as a Windows printer -- which means that you can create PDF files from any old program that can print!
* * * Do you have a favorite application that you use to help run your small business? Share it with us in the comments!
